1. Field of the Invention
This invention relates to a card printing method and a card printing apparatus which are capable of carrying out so-called beyond-edge printing on a card having a predetermined thickness.
2. Prior Art
Conventionally, a card printing method and a card printing apparatus of this kind have been proposed in Japanese Laid-Open Patent Publication (Kokai) No. 11-254657, which feed a card placed on a tray in one direction, and at the same time cause a print head to reciprocate in a direction orthogonal to the direction of feed of the card, thereby carrying out beyond-edge printing for ejecting ink droplets onto areas outside the opposite edge portions of the card. In this case, the card is placed on the tray such that it is fit into a shallow rectangular groove in an ink absorbent material arranged on the top of the tray, and the ink droplets ejected onto areas beyond the opposite edge portions of the card are absorbed by the ink absorbent material such that they are prevented from adhering to end faces of the card at the edges.
In the conventional card printing method and apparatus configured as above, adhesion and drying of ink repeatedly occurs in the ink absorbent material, so that this material suffers from clogging as time elapses. If the ink absorbent material is clogged as described above, the ink is sucked in contact portions between the ink absorbent material and the card by capillary action, thereby causing ink to readily adhere to the end surfaces of the card on the contrary.
On the other hand, as shown in FIGS. 12A and 12B, when a print head 101 reciprocates while ejecting ink droplets A, the ink droplets A are ejected onto a card C in a relatively slanting direction to the direction of movement of the print head 101. If beyond-edge printing is carried out in a state in which the ink droplets A are ejected as above, the ink droplets A are actively caused to hit an end face on a rear side of the card C in the direction of movement of the print head 101. As a result, the ink positively adheres to the end face.
It is an object of the invention to provide a card printing method and a card printing apparatus which are capable of preventing or minimizing the possibility of adhesion of ink to end faces of a card.
To attain the above object, according to a first aspect of the invention, there is provided a method of printing on a card having a predetermined thickness by using a print head by an ink jet printing method.
The method according to the first aspect of the invention is characterized by comprising the steps of:
reciprocating moving the print head; and
carrying out beyond-edge printing in which ink droplets are ejected beyond opposite edges of the card, immediately before termination of ejection of the droplets when the print head is moved in one direction, and immediately before termination of ejection of the droplets when the print head is moved in another direction opposite to the one direction.
To attain the above object, according to a second aspect of the invention, there is provided a card printing apparatus for printing on a card having a predetermined thickness by an ink jet printing method.
The card printing apparatus according to the second aspect of the invention is characterized by comprising:
a card feed mechanism for feeding the card;
a print head for carrying out printing on the card being advanced, while performing reciprocating motions; and
a controller for controlling the card feed mechanism and the print head,
the controller causing the print head to carry out beyond-edge printing in which ink droplets are ejected beyond opposite edges of the card, immediately before termination of ejection of the droplets when the print head is moved in one direction, and immediately before termination of ejection of the droplets when the print head is moved in another direction opposite to the one direction, if the beyond-edge printing is required.
According to the above card printing method and card printing apparatus, when beyond-edge printing is to be carried out at one edge of a card, the beyond-edge printing is carried out immediately before termination of ejection of ink droplets when the print head is moved in one direction, for instance, whereas when beyond-edge printing is to be carried out at an another edge of the card opposite to the one edge, the beyond-edge printing is carried out immediately before termination of ejection of ink droplets when the print head is moved in the other direction. In other words, beyond-edge printing on the edge portions of the card is not carried out immediately after the start of the ejection of ink droplets not only when the print head is moved in one direction but also when the print head is moved in the other direction.
The print head carries out printing operations by ejecting ink droplets during reciprocation, and therefore ink droplet shit (are ejected onto) the card from a relatively slanting direction. Therefore, if beyond-edge printing is carried out on the edge portions of the card immediately after the start of the ejection of ink droplets, the ink droplets hit the end faces of the end portions as well. In contrast, if beyond-edge printing is carried out on the edge portions of the card immediately before termination of ejection of ink droplets, the ink droplets do not hit the end faces of the end portions.
Preferably, a printing area printed when the print head is moved in the one direction and a printing are a printed when the print head is moved in the another direction opposite to the one direction extend from an intermediate portion of the card to the opposite edges of the card.
Preferably, the controller controls the card feed mechanism and the print head such that a printing area printed when the print head is moved in the one direction and a printing area printed when the print head is moved in the another direction opposite to the one direction extend from an intermediate portion of the card to the opposite edges of the card.
According to these preferred embodiments, in each printing operation during the advancing and returning motions of the print head, ejection of ink droplets is always started from the intermediate portion (preferably, a center line) of the card and terminated at locations beyond edge portions of the card, so that it is possible to cause the printing to be each time effected on approximately one of left and right halves of the whole card surface, by simple control.
In general, it is preferred that whenever the print head prints on one line, printing is carried out on approximately one half of the line on the card. If the card can be fed such that it is reciprocatingly moved, however, approximately one half of the whole card may be printed in each of forward and rearward printing operations.
Preferably, a printing area printed when the print head is moved in the one direction and a printing area printed when the print head is moved in the another direction opposite to the one direction overlap each other to form an overlapping area.
Preferably, the controller controls the card feed mechanism and the print head such that printing area printed when the print head is moved in the one direction and a printing area printed when the print head is moved in the another direction opposite to the one direction overlap each other to form an overlapping area.
According to these preferred embodiments, the left-hand side printing area and the right-hand side printing area are caused to overlap each other, whereby it is possible to prevent a faulty printing operation, such as thinned dots at the intermediate portion (boundary portion) of the card in comparison with the case in which printing is carried out for one half of the card each time. In short, inconsistencies in density at the boundary portion between the left-hand side and right-hand side printing areas can be eliminated.
Preferably, an amount of ink droplets ejected onto the overlap area per unit image and an amount of ink droplets ejected onto each non-overlapping area per unit image are adjusted to an identical amount.
Preferably, the controller adjusts an amount of ink droplets ejected onto the overlapping area per unit image and an amount of ink droplets ejected onto each non-overlapping area per unit image to an identical amount.
According to these preferred embodiments, it is possible to prevent color perception (print density) from changing between an image printed on the overlapping portion and an image printed on each non-overlapping portion. For instance, if the amount of ink droplets ejected onto each non-overlapping portion per unit image is set to 10, in the overlapping portion, the amount of ink droplets ejected during an advancing motion of the print head, and the amount of ink droplets ejected during a returning motion of the print head are set to 5, respectively. Alternatively, instead of setting the same amount, it is possible to set the amount ejected to the overlapping portion during an advancing motion to 7, and the amount ejected to the same during a returning motion to 3. Further, the amount of ink droplets ejected per unit image may be increased as the printing area is shifted to the non-overlapping portion.
Preferably, the printing is carried out by using a surface of the card having a droop portion formed thereon by blanking, as a recording surface for the printing.
Preferably, the card feed mechanism guides the card such that a surface of the card having a droop portion formed thereon by blanking, is used as a recording surface for printing.
According to these preferred embodiments, when a card is formed by blanking, an edge of one surface is raised sharply and slightly in the form of burrs. When the surface with this droop portion in the form of burrs is used as a recording surface for beyond-edge printing, it is possible to prevent ink droplets having hit an edge portion from flowing down an end face since the droop portion serves as a wall or a barrier to stop the flow of ink. That is, it is possible to prevent the ink droplets from adhering to an end face of the card.
Preferably, the method includes the step of tilting the card in a direction of movement of the print head such that the card lowers in a direction of movement during each printing operation carried out when the print head is moved in the one direction and when the print head is moved in the another direction opposite to the one direction.
Preferably, the card printing apparatus further includes a tilting mechanism for tilting the card brought to the print head such that the card performs sea-sawing motion, the tilting mechanism tilting the card in a direction of movement of the print head such that the card lowers in a direction of movement during each printing operation carried out when the print head is moved in the one direction and when the print head is moved in the another direction opposite to the one direction.
According to these preferred embodiments, the card is physically tilted, whereby hitting angles of ink droplets with respect to a direction perpendicular to the card surface can be relatively increased, thereby making it possible to minimize hitting of ink droplets onto end faces and adhesion thereof.
Preferably, the print head ejects ink droplets adjusted to be very fine, at least when printing is carried out on each of the opposite edges of the card.
Preferably, the controller causes the print head to eject ink droplets adjusted to be very fine, at least when printing is carried out on each of the opposite edges of the card.
According to these preferred embodiments, fine ink droplets are difficult to flow due to surface tension thereof. This makes it possible to prevent ink droplets having hit edge portions of the card from flowing toward end faces to the utmost.
Preferably, the method includes the step of wiping off ink adhering to end faces at the opposite edges of the card while advancing the card after termination of printing.
Preferably, the card printing apparatus further includes a wiping device arranged to face the card being advanced by the card feed mechanism after termination of printing, for wiping off ink adhering to end faces at the opposite edges of the card.
According to these preferred embodiments, for instance, when the printed card is delivered out of the apparatus, the opposite edge portions of the card are wiped out by making use of a card feeding operation, whereby it is possible to provide a card which does not cause the user to feel a sense of disorder.
Preferably, the method includes the step of scraping ink adhering to end faces at the opposite edges of the card while advancing the card after termination of printing.
Preferably, the card printing apparatus further includes a scraping device arranged to face the card being advanced by the card feed mechanism after termination of printing, for scraping off ink adhering to end faces at the opposite edges of the card.
According to these preferred embodiments, even if it is difficult to wipe off the ink adhering to the opposite edge portions of the card, the ink can be reliably removed, thereby making it possible to provide an attractive card which does not cause the user to feel a sense of disorder.
To attain the above object, according to a third aspect of the invention, there is provided a card printing apparatus for printing on a card having a predetermined thickness by an ink jet printing method.
The card printing apparatus according to the third aspect of the invention is characterized by comprising:
a card feed mechanism for feeding the card;
a print head for carrying out printing on the card being advanced, while performing reciprocating motions; and
a controller for controlling the card feed mechanism and the print head,
the card feed mechanism including feed roller means arranged at a location upstream of the print head in a direction of feed of the card and delivery roller means arranged at a location downstream of the print head in the direction of feed of the card,
the controller controlling card feeding operations of the feed roller means and the delivery roller means such that the feeding operations are made synchronous with printing operations carried out by the print head.
According to this card printing apparatus, when the print head is carrying out a printing operation, the card feeding operations of the feed roller means and the delivery roller means are controlled, so that, for instance, even if the printing operation is started before the leading edge of the card reaches the delivery roller means, and even if the trailing edge of the card leaves the feed roller means when the printing operation is being continued, the card feeding operations are carried out with accuracy. Therefore, when beyond-edge printing is carried out on the opposite edge portions of the card on the leading edge side and the trailing edge side in the direction of feed of the card, forming of thinned dots can be prevented, and the beyond-edge printing can be carried out with accuracy.
The above and other objects, features, and advantages of the invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.